1. Field of the Invention
The present invention relates to an electronic cartridge that contains an integrated circuit package(s).
2. Background Information
FIG. 1 shows an electronic cartridge that includes an integrated circuit package 1 which is mounted to a printed circuit board 2. The package 1 contains one or more integrated circuits (not shown). One edge of the circuit board 2 may have a plurality of conductive pads (not shown) that can be plugged into a card edge connector. The card edge connector may be mounted to a motherboard of a computer system.
The assembly may include a thermal plate 3 that is thermally coupled to the integrated circuit package 1. A heat sink (not shown) may be attached to the thermal plate 3 to facilitate the removal of heat generated by the integrated circuits. The printed circuit board 2 may be enclosed by a cover 4.
The integrated circuit generates heat that may flow into the thermal plate 3 through a metal lid 5 of the package 1. Manufacturing tolerances of the assembly may create an air gap between the lid 5 and the thermal plate 3. Air has a relatively low coefficient of thermal conductivity. The existence of an air gap may increase the temperature drop from the package 1 to the thermal plate 3 and the junction temperatures of the integrated circuit.
A thermal grease is typically inserted between the lid 5 and the thermal plate 3 to reduce the temperature drop across the assembly and the junction temperatures of the integrated circuit. Even with the application of a thermal grease the thickness of the space between the lid 5 and the thermal plate 3 may differ between assemblies because of variations in part tolerances. The varying space thickness reduces the predictability of the thermal interface resulting in different junction temperatures for different assemblies. It would be desirable to provide a design that creates a minimum space thickness or bondline for the thermal grease of each assembly.